A femtocell base station is designed to connect user equipment located in a femtocell to a service provider's network. A femtocell may denote a small service area covered by a femtocell base station. For example, the femtocell may be a home or a small business office in a cellular system. The range of a femtocell base station may be about 10 meters. The femtocell base station has been applied to a Long Term Evolution (LTE) communication network. The 3rd Generation Partnership Project (3GPP) has introduced standard-specifications for LTE technology. In 3GPP LTE standard specifications, the femtocell base station has been defined as well as a macrocell base station. The femtocell base station may be referred to as a Home NodeB (HNB) for a 3G femtocell or as a Home Evolved Node Base station (HeNB) for an LTE femtocell. The macrocell base station may be referred to as an evolved NodeB (eNB).
3GPP LTE standard specifications also define an X2 interface. The X2 interface may be a logical interface between two macrocell base stations, such as eNBs. For example, the X2 interface may be a point to point link between eNBs, but a physical relation thereof need not be a point to point link. The X2 interface may allow eNBs to be interconnected with each other. The macrocell base stations may exchange signaling information including control data through the X2 interface. That is, the macrocell base stations may perform handover and load balancing by exchanging information through the X2 interface. Particularly, the X2 interface may enable functions of mobility management, load management, inter-cell interference coordination, general X2 management and error handling, application level data exchange between eNBs, and Trace function.
As described above, the X2 interface may provide various functions and macrocell base stations may be efficiently managed through many management tasks of the X2 interface. Femtocell base stations may perform various tasks similar to those of macrocell base stations. Femtocell base stations may need the functions of the X2 interface in order to exchange signal information, for handover, and/or for load balancing. However, the 3GPP LTE standard specification does not define an X2 interface for femtocell base stations such as, for example, HeNBs or HNBs.